Compressed-air power system.



B. V. NORDBERG.

COMPRESSED AIR POWER SYSTEM.

APPLICATION FILED JAN.29, 1912.

mamm

Patented June 26, 1917.

3 SHEETS-SHEET vI Invenor;

Wiifinesses;

B. V. NORDBERG.

COMPRESSED AIR POWER SYSTEM.

APPLICATION FILED JAN-29,1912.

Patented June 26, 191]. 3 SHEETS-SHEET 23"" Wd KMSQS W mm @:%m,,

8.; v. NORDBERG. COMPRESSED AIR POWER SYSTEM.

APPLICATION FILED JAN.29, l9l2. 1,231,51.

Patented June 26, 1917-.

3 SHEETSSHEET a.

777-1317101366 e '5' gave/nib? 4 WW QM fl w 4% BRUNO V. NORDBERG, F MILWAUKEE, WISCONSIN.

COMPRESSED-AIR. rowan. SYSTEM.

Specification of Letters Patent. Patented June 26, 1917.

1 Application filed January 29, 1918; Serial No. 674,056.

To all whom it may concern:

Be it known that I, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain,

new and useful Improvements in Compressed-Air Power Systems, of which the following is a specification, reference being had to the accompanying drawing, forming apart thereof.

This invention relates more particularly to compressed air systems upon which the demand for power as for example, in operating hoisting engines, fluctuates often within wide limits.

The main objects of the present invention are to equalize the load upon the air compressing lant of such a system; to enable a plant t e capacity of which is equal-to the average demand for power thereon to temporarily supply any and all excess or extraordinary demands to which the system may be subjected, such as peak loads in the operation of hoistin engines; and thus to admit of reducing t e size of the air com pressing plant and the cost of installing,

operating and maintaining the same.

It consists in the construction,-arrangement and combination of arts or elements for the accomplishment o these'objects, as hereinafter particularly described and pointed out in the'claims.

In the accompanying drawing like characters designate the same parts in the several figures.

Figure 1' is a diagrammatic view of aparatus embodying the invention; Fig. 2 1s a side elevation on an enlarged scalemf a variable capacity compressed air engine of the type shown in United States Letters Patent No. 926,819 issued to me July 6, 1909, and suitabl for use in and as a part of the apparatus constituting the present invention; and Fig. 3; is an axial section on a still larger scale of a cylinder with an ar-' rangement of Valves suitable for such -an engine. p

In the operation of ahoisting engine the load is usually extremely variable or fluctuating,both in regard to individual trips and also to the distribution of the power over any given period of time.- Ateaoh tripiwhenthe load is started, a certain amount of power must be applied to accelerate the hoist. This power is often two or 7 three tiines greater than that required to Bruno V. Nounnnno,

balance the load. When the hoist has been 7 in -a brake or bya' retarding power such for example as is described in the above mentioned patent;

A *certain interval of time is required to load and unload the skips or cages connected with the hoist, during which time the engine remains idle and no power is consumed.

Thehoisting is generally done during certain parts of the day, whileduring other parts of the day very little work is done with the hoisting engine except that necessary to lower the miners into and lift them out of the mine at the change of shifts;

Due to these conditions, the hoist is seldom in operation more than half of the time, and frequently much less. The result of this is that while, as in several instances within my knowledge, the efi'ective Work represented by the lift ng of the loads averages per day one hundred horse power, the

- same work distributed over the actual time is drawn from them, only a part of the energy stored in the air in said tanks can be utilized. For instance, if the pressure-1n said tanks is one hundred pounds, it would a not be practicable to draw therefrom a greater quantity of air than would reduce the pressure below say, eighty pounds, or

that required to properly operate the engine.- It follows therefore, that in the case assumed, only, one-fifth of the total volume of the expansion tank or tanks is available for stora e. Such expansion tanks are however, in ispensable in connection with a system of hoisting en ines, to take care of the sudden and great emands for air when the hoists are accelerated. The quantity of air required to meet such sudden and great demands is between five and tentimes greater than that required when the hoist is up to speed, but the time durin which such great quantity is required, is s ort, so that under thes conditions an expansion tank is the proper device to use in connection with the hoist, and such tank should be located close to the hoist, so that the pipe system may not be overtaxed by such extraordinary demands for air.

In order however, to completely equalize the load or in j,order to render it possible for an air-compressor the capacity'of which is equal to the average consumption of all the hoists connected therewith to supply such extraordinary demands for air, the hydrostatic equalizing device herein shown and describedhas been devised.

Referring toFig; 1 of the drawing, a designates an air'compressor which may be driven by a steam engine or other motor. 0 is an expansion tank located close to the comprcssor'and connected by a pipe at with the discharge chest thereof. 0 is another expansion tank located near a hoisting engine 7'' and connected by a pipe 1 with the tank 0. These ex )ansion tanks 1 and 8 being located close to t e compressor a and en ine f, tend to equalize the pulsations and uctuations of pressure due to theaction of the compressor and the action of the engine, especially when the latter is subjected to sudden .and extraordinary increase of load, and

thus prevent consequent Waste of energy and overtaxing the piping of the system. The hoisting engine, which may be and .preferably is, of the type described in the patent hereinbefore mentioned, ispreferably connected with the tank e through a heater h, by which theair passin from the tank e to the engine is heated, whle the compressed air discharged by the engine when it acts as a, compressor to develop retarding accordmg to said patent, will be con ucted into 'said tank around the heater through a branch pipe or bypass 2';

The pipe connection between the engine 1 and the heater h is provided with a check valve 2, which closestoward the heater, and the branch pipe or by-pass z leading from said pipe connection back to the tank e is provided with a check valve 3, which closes toward the engine.

An air receiver j of large size, which when the conditions are such that it can be done, may be excavated in the rock formation below the surface, is connected at the top .by a pipe or conduit k with the pipe 9',

or with a part of the compressed air systein between the com ressor and engine.

A water tank having a capacity equal to or as eat as that ofthe air receiver 9' and locate above the same, is connected at or near the bottom by a. pipe or conduit m with .the bottom or lower part of ,said'renecessary-to operate the hoisting engine or other apparatus connected with the system and the size and shape of the tank and receiver are such that the Water level in the tank will vary but little and hence the hydrostatic pressure on the air in the receiver will remain substantially constant, whatever the volume of water in the receiver may be.

Referring to Figs. 2 and 3 showing a compressed air engine of variable capaclty, capable of developing greater power than can be supplied by the maximum capacity of the compressor a, and convertible at will from a motor into a compressor and vice versa, the engine comprises one or more cylinders 4, but one being shown in the present case. Each cylinder is provided,

as shown in Fig. 3, with a piston 5, inlet close the valves, oscillatory opening arms 12 mounted concentrically with the valve stems, trip arms 13 pivotally mounted on the'arms 12 and adapted by engagement with the arms 10 to open the valves, and cams 14 pivotally mounted on the arms 12 shown, with the crank shaft 17 of the enand engaging with the trip arms 13. The arms 12 are actuated by wrist plates '15 and an eccentric 16 which may be connected, as

ine by reversing gear 18 manually adjusted by a suitable device such as a lever flhe cams 14 are connected with weighted trip levers 20 and 21, which are connected with and manually operated and controlled by a lever 22 or other suitable means.

a When the lever 22 and the valve releas- 1 ing mechanism are'adjusted as shown in. Fig. 2, compressed air will be admitted to the ex anding end .of the cylinder and exhausts from the other end of the cylinder durlng nearly the full stroke of the piston, the inlet and exhaust valves 6 and 7 being opened and held open by the valve gear.

the inlet valves 6 will be released and closed earlier in the stroke of the piston, thereby gradually reducing the volume of airadmitted to the cylinder and hence reducing the driving or accelerating power applied to the engine until further movement of upper trlp cams 14 by the weighted lever v20 is arrested by a stop 23, in position to prevent the opening of said valves and the further admlsslon of compressed air into the cylinder, the exhaust valves continuing.

to function as-bei'ore.

A further movement of the lever 22 in the same direction, shifts the trip lever 21 and turns the lower cams 14 into position to release the exhaust valves 7 and permit them to close, at first near the end of the stroke of the piston, thereby converting the engine from a motor into a compressor.

The continued movement of the lever 22 in this direction ,efl'ects an earlier closing of the exhaust valves, thereby gradually increasing the work and the retarding -or braking effect to which the engine is subjected without waste of power, until at the limit of the movement of said lever to the left the cams 1.4: reach a position in which they will, not open said valves.

The movement of the lever 22 backward to the right effects a reversal of the foregoing operations, gradually reducing the work or retarding efiect on the engine functioning as a compressor, then converting the engine from a compressor into a motor and then gradually increasing the driving or accelerating power applied to the engine functioning as a motor.

When the engine operates as a motor and the valve gear is adjusted for early release of the inlet valves 6, the automatic suction valves 8 operate to prevent expansion of the air in the cylinder. below atmospheric or exhaust pressure and thus avoid waste of power, and when the engine operates as a compressor both the suction and discharge valves 8 and 9 operate, as more fully explained in said Letters Patent-No. 926,819.

In the operation of the apparatus, when compressed air is drawn therefrom at a greater rate than the compressor a which runs at an approximately constant speed, can supply, the excess is taken from the receiver j, and as thepressure in said receiver is slightly lowered, the water from the tank Z flows through the pipe or conduit m into said receiver. It is obvious that with this arrangement it is possible to draw on the whole storage volume of the receiver 3', which if it is made large enough, ill render it possible to operate the compressor a at a constant speed and still supply the.

the.

To, control the operation of the compressor andprevcnt wasteof power, the tank I is provided with a float n, which normally rests on the supports 0, and this float, which may be in practice made in the form of a heavy raft of logs or timbers, so that it will not be sensitive to friction, but will act with considerable power when lifted by a rise of the level of the water in said tank, may control the supply of steam or other power by which the compressor is actuated or the volume of air compressed by a compressor of variable capacity, such for instance, as is shown and described in Patent No. 900,418 issued to me October 6, 1908.

In the drawing the float is shown as connected by a rope. 3) passing over sheaves g with a lever 1' which controls the supply of steam to the compressor engine. A. counterpoise 8 attached to the rope p, keeps it stretched taut and acts upon the lever r in opposition to the weight of the float a, which is much greater than that of the counterpoise. The float may be connected with mechanism for varying the capacity of the compressor, such as that shown in Patent 900,418 above mentioned. The connecit rests in its normal position on the supports 0 it will allow the compressor to run at full capacity, but whenever the level of the water rises sufliciently to lift the float, it will reduce the speed or capacity of the compressor, thus operating as a safety device and preventing escape and loss of air pressure when the hoisting engine is shut down or the consumption of compressed air ceases for a considerable length of time.

In the operation of the apparatus disclosed and claimed in this application, after establishment of the air pressure which balances the water column, nearly the whole quantity of stored compressed air which has been delivered from the compressor, is available for use in meeting the widely varying demands of the engine 7. in establishing and maintaining that condition substantially the same power must be used as that required to establish and maintain the average pressure in the air reservoir of the aforesaid Letters Patent No. 926,819, but in the present case the foundation pressure used immediately in the operation of the engine, is not that of an elastic fluid, but is' that of a moving incompressible body, the

water column in the tank Z and conduit m,

and any required quantity of air within the sure of air supplied.

In the apparatus of said Letters Patent No. 926,819, the volume of stored air is constant, while the pressure varies widely, whereas in the resent system the pressure ofthe stored air is substantially constant, while the volume varies within wide limits.

In the adaptation of the apparatus to varying conditions to meet diflerent requirements, the construction and arrangement of its component elements may be changed ac cordingly without aii'ecting the principle and mode of operation of the equalizing device and without departure from the scope of the invention.

I claim:

1. In a compressed air power system the combination with a compressed air engine of an air compressor, an air receiver connected with the discharge of the compressor and having a manually controlled connection with the engine, and an open water tank located above and having a constantly open and unobstructed connection with the air receiver, said receiver and tank being so constructed, arranged and connected that a quantity of compressed air equal to the entire volume of the receiver may be drawn therefrom at an approximately constant pressure.

2. In a compressed air power system the combination with a compressed air engine of an air compressor, an air receiver connected with the discharge of the compressor and having a manually controlled connection with the engine, and an open Water tank having an unobstructed and constantly open connection with said air receiver and leeated at such a distance above the same as is required to maintain a hydrostatic pres sure approximatel equal to the normal discharge pressure 0 the compressor.

3. In a compressed air power system, the combination of an air :om ressor, a com pressed air engine of variab e capacit con- I nected with the compressor and capa le of developing greater power than can be directly supphed by the maximum ca acity of the compressor, an air receiver of arge capacity connected with the compressed air supply conduit between the compressor and engine, and an open water tank having an unobstructed and constantly open connection, with said receiver and located above the same at a suflicient distance to balance the normal working pressure in the system.

4. In a compressed air power system the combination of an air compressor, a compressed air engine connected with the compressor, an air expansion tank in the connection between the compressor and engine, an air receiver connected with the air conduit between the compressor and engine, and an open Water tank located above and having an unobstructed and constantly open connection with said receiver.

5. In a compressed air power system the combination with a compressed air engine of anair compressor, an air receiver connected with the dischargeof the compressor and with the engine, an. open Water tank I located above and having a'constantl open connection with said receiver, and a oat in said tank adapted when the water rises above a certain level therein to reduce the volume of air discharged by the compressor.

6. In a compressed air power system the combination with a'compressed air engine of an air compressor, an expansion tank in communication with the discharge of the compressor and connected with the compressed air driven engine, an air receiver connected with the discharge of the compressor and with the engine, and an open Water tank of as great capacity as the receiver located above the same and connected with the lower part thereof by an unobstructed and constantly open conduit extending below the receiver.

7. In a compressed air power system, the combination of an air compressor, a compressed air engine, an expansion tank supplied with air from the compressor and supplying compressed air to the engine to drive the latter, an air receiver connected with the compressed air conduit between the cornpressor and engine to supply compressed air to the engine when the demand thereof exceeds the ca acity of the compressor and expansion tan and a hydrostatic device cooperatively connected with the air receiver to equalize the pressure therein proportionately to withdrawal of air therefrom.

In witness whereof I hereto afiix my signature in presence of two witnesses.

BRUNO V. NORDBERG. Witnesses GHAs. L. Goss, FRANK E. DENNETT. 

